新型Ni-Cr-Mo高强耐蚀合金中碳化物热稳定性的研究  

Study on Thermal Stability of Carbides in a New Corrosion- Resistant Ni-Cr-Mo Alloy with High Strength

作　　者：曾燕屏[1] 寇立忠[1] 谢锡善[1] 

机构地区：[1]北京科技大学,北京100083

出　　处：《稀有金属材料与工程》2013年第12期2494-2498,共5页Rare Metal Materials and Engineering

基　　金：美国海因斯国际公司(Haynes International Inc.;USA)

摘　　要：采用SEM、TEM和化学相分析等手段研究了一种新型Ni-Cr-Mo高强耐蚀合金中碳化物的热稳定性,结果表明:标准热处理态下的新合金由大小不均匀的等轴晶组成,其中的碳化物主要为聚集分布的颗粒状Mo6C。在600℃时效时,Mo6C相的形态、尺寸和数量均无明显变化,这表明它在该温度下具有较好的热稳定性。但在650℃时效时,随着时效时间的延长,Mo6C相的形态将逐渐由颗粒状向片状转变,当时效时间超过500 h后,它将逐渐溶解,与此同时条状的Cr23C6相将在合金晶界逐渐析出。这表明Mo6C相在该温度下是不稳定的,故新合金的使用温度应低于650℃。Thermal stability of carbides in a new corrosion-resistant Ni-Cr-Mo alloy with high strength was studied by means of OM, SEM, TEM and chemical phase analysis. Results show that the microstructure of the alloy on standard heat treatment condition consists of equiaxed grains of f.c.c γ, with an average size of 50 μm. Second phase particles of various sizes ranging from 100 nm to 2 μm are not only presented at grain boundaries, but also randomly distributed in grain interiors and were identified as the Mo6C and μ phases, respectively. After exposure for 10-1000 h at 600 ℃, almost no change in their morphologies, phase particle sizes and distribution can be seen, which implies that the Mo6C and μ phases are stable during aging at 600 ℃. However, their morphologies change gradually from granular to plate-like during exposure of up to 500 h at 650 ℃. Beyond 500 h the Mo6C and μ phases will dissolve gradually and meanwhile, the continuous precipitates Cr23C6 are formed at the grain boundaries, which indicates that the Mo6C and p phases are not stable during aging at 650 ℃ and the service temperature of the new alloy should be lower than 650 ℃.

关 键 词：Ni-Cr-Mo合金 碳化物 热稳定性 

分 类 号：TG146.15[一般工业技术—材料科学与工程]